The present invention relates to a tape cartridge in which a tape reel includes a pair of upper and lower flanges and a hub for winding a tape thereonto.
In the tape reel composed of a pair of upper and lower flanges and a hub, one side of the hub is often molded integrally with one of the flanges, while the other flange is fixed to the hub. In the conventional tape reel, the latter flange is fixed to the end face of the hub by ultrasonic welding (see JP 2006-65987 A and JP H7-5591 Y).
In the above fixing structure in which the flange is fixed by ultrasonic welding, a deposited piece is melt and deformed with frictional heat relating to supersonic vibration, and therefore it is inevitable that the remaining stress from the time of flange molding is locally relaxed by melting heat of the deposited piece. Consequently, even if there was no problem in molding precision of the flange before ultrasonic welding, a part of the flange have sometimes deformed toward the thickness direction, or the angle of gradient of the flange face have changed locally after ultrasonic welding, which caused a problem in enhancing the finishing precision of the tape reel.
What is necessary for preventing the deformation of the flange relating to such ultrasonic welding is, for example, to mold the flange in anticipation of the release and deformation of the remaining stress. To this end, however, test molding and correction of a metallic mold need to be repeated, which takes long time and large costs. Further, since the deformation amount of the flange differs with variation in form of the deposited piece or with a slight difference in excitation conditions by a welding horn, there are limitations in enhancing the form accuracy of the flange which is to be fixed by welding, even if the flange is molded in anticipation of the release of the remaining stress.